METHOD OF FABRICATING BACKSIDE-ILLUMINATED IMAGE SENSOR

• US 20110108940A1
• Filed: 11/06/2009
• Published: 05/12/2011
• Est. Priority Date: 11/06/2009
• Status: Active Grant

• Current Assignee: Taiwan Semiconductor Manufacturing Company Limited
• Original Assignee: Taiwan Semiconductor Manufacturing Company Limited
• Inventors: Huang, Chen-Ming, Yuang, Dun-Nian, Wu, Chih-Jen, Huang, Kuan-Chieh
• Granted Patent: US 8,283,745 B2
• Time in Patent Office: Days
• US Class Current: 257/447
• CPC Class Codes: H01L 21/6835 using temporarily an auxiliary support
• CPC Class Codes: H01L 2221/68327 used during dicing or grinding
• CPC Class Codes: H01L 2221/68363 used in a transfer process involving transfer directly from an origin substrate to a target substrate without use of an intermediate handle substrate
• CPC Class Codes: H01L 2221/68381 Details of chemical or physical process used for separating the auxiliary support from a device or wafer
• CPC Class Codes: H01L 2224/02313 Subtractive methods
• CPC Class Codes: H01L 2224/0239 Material of the redistribution layers
• CPC Class Codes: H01L 2224/024 Material of the insulating layers therebetween
• CPC Class Codes: H01L 2224/0401 Bonding areas specifically adapted for bump connectors, e.g. under bump metallisation [UBM]
• CPC Class Codes: H01L 2224/131 with a principal constituent of the material being a metal or a metalloid, e.g. boron [B], silicon [Si], germanium [Ge], arsenic [As], antimony [Sb], tellurium [Te] and polonium [Po], and alloys thereof
• CPC Class Codes: H01L 2224/45015 being circular
• CPC Class Codes: H01L 2224/45099 Material
• CPC Class Codes: H01L 2224/48 of an individual wire connector
• CPC Class Codes: H01L 2224/81191 wherein the bump connectors are disposed only on the semiconductor or solid-state body
• CPC Class Codes: H01L 2224/81801 Soldering or alloying
• CPC Class Codes: H01L 2224/85 using a wire connector
• CPC Class Codes: H01L 23/49805 the leads being also applied on the sidewalls or the bottom of the substrate, e.g. leadless packages for surface mounting
• CPC Class Codes: H01L 24/02 Bonding areas on insulating substrates, e.g. chip carriers, H01L23/49816, H01L23/49838, H01L23/5389; Manufacturing methods related thereto
• CPC Class Codes: H01L 24/05 of an individual bonding area
• CPC Class Codes: H01L 24/16 of an individual bump connector
• CPC Class Codes: H01L 24/81 using a bump connector
• CPC Class Codes: H01L 24/85 : using a wire connector wire bonding in general B23K20/004
• CPC Class Codes: H01L 27/14618 : Containers
• CPC Class Codes: H01L 27/14621 : Colour filter arrangements
• CPC Class Codes: H01L 27/14627 : Microlenses
• CPC Class Codes: H01L 27/1464 : Back illuminated imager structures
• CPC Class Codes: H01L 27/14645 : Colour imagers
• CPC Class Codes: H01L 27/14687 : Wafer level processing
• CPC Class Codes: H01L 27/14689 : MOS based technologies
• CPC Class Codes: H01L 2924/00 : Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/00014 : the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 2924/01019 : Potassium [K]
• CPC Class Codes: H01L 2924/01022 : Titanium [Ti]
• CPC Class Codes: H01L 2924/01028 : Nickel [Ni]
• CPC Class Codes: H01L 2924/01029 : Copper [Cu]
• CPC Class Codes: H01L 2924/01087 : Francium [Fr]
• CPC Class Codes: H01L 2924/01327 : Intermediate phases, i.e. intermetallics compounds
• CPC Class Codes: H01L 2924/014 : Solder alloys
• CPC Class Codes: H01L 2924/10253 : Silicon [Si]
• CPC Class Codes: H01L 2924/12043 : Photo diode
• CPC Class Codes: H01L 2924/14 : Integrated circuits
• CPC Class Codes: H01L 2924/1461 : MEMS
• CPC Class Codes: H01L 2924/207 : Diameter ranges
• CPC Class Codes: H01L 31/0232 : Optical elements or arrangements associated with the device H01L31/0236 takes precedence; for photovoltaic cells H01L31/054; for photovoltaic modules H02S40/20
• CPC Class Codes: H01L 31/18 : Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof
• CPC Class Codes: H05K 2201/10151 : Sensor
• CPC Class Codes: H05K 3/3436 : having an array of bottom contacts, e.g. pad grid array or ball grid array components

Abstract

Provided is a method of fabricating a backside illuminated image sensor that includes providing a device substrate having a frontside and a backside, where pixels are formed at the frontside and an interconnect structure is formed over pixels, forming a re-distribution layer (RDL) over the interconnect structure, bonding a first glass substrate to the RDL, thinning and processing the device substrate from the backside, bonding a second glass substrate to the backside, removing the first glass substrate, and reusing the first glass substrate for fabricating another backside-illuminated image sensor.

Claims

1. A method of fabricating a backside-illuminated image sensor, the method comprising:

providing a device substrate having a frontside and a backside, wherein a plurality of pixels are formed at the frontside and an interconnect structure is formed over the pixels;

forming a re-distribution layer (RDL) over the interconnect structure;

bonding a first glass substrate to the RDL;

thinning and processing the device substrate from the backside;

bonding a second glass substrate to the backside;

removing the first glass substrate; and

reusing the first glass substrate for fabricating another backside-illuminated image sensor.

2. The method of claim 1, further comprising:

dicing the device substrate to form a chip that includes the backside-illuminated image sensor; and

coupling the RDL to a board for packaging the chip, wherein the RDL layer is coupled to the interconnect structure.

3. The method of claim 1, wherein the processing the device substrate from the backside includes:

forming a color filter layer on the thinned backside of the device substrate; and

forming a microlens layer on the color filter layer;

wherein the bonding the second glass substrate includes bonding the second glass substrate over the thinned backside of the device substrate such that a cavity is formed between the second glass substrate and the device substrate, wherein the color filter layer and the microlens layer are disposed within the cavity.

4. The method of claim 3, wherein the cavity is filled with one of air and epoxy.

5. The method of claim 1, wherein the bonding the first glass substrate includes applying an adhesive coating on the RDL and bonding the first glass substrate for thinning and processing the device substrate from the backside.

6. The method of claim 1, wherein the removing the first glass substrate includes de-bonding the first glass substrate at a temperature greater than a temperature used for bonding the first glass substrate.

7. The method of claim 1, further comprising forming a passivation layer between the interconnect structure and the RDL.

8. A backside-illuminated image sensor, comprising:

a device substrate having a frontside and a backside;

a plurality of pixels disposed at the frontside of the device substrate;

an interconnect structure disposed over the pixels;

a re-distribution layer disposed over the interconnect structure, wherein the RDL is coupled to the interconnect structure; and

a glass substrate bonded to the backside of the device substrate.

9. The image sensor of claim 8, further comprising a board for coupling to the RDL for chip packaging.

10. The image sensor of claim 8, further comprising:

a color filter layer disposed over the backside of the device substrate and aligned with pixels; and

a microlens layer disposed over the color filter layer;

wherein a cavity is formed between the glass substrate and the device substrate and wherein the color filter layer and the microlens layer are disposed within the cavity.

11. The image sensor of claim 10, wherein the cavity is filled with one of air and epoxy.

12. The image sensor of claim 8, further comprising a passivation layer disposed between the interconnect structure and the RDL.

13. A backside-illuminated image sensor, comprising:

a device substrate having a frontside and backside;

a plurality of pixels disposed at the frontside of the device substrate;

an interconnect structure disposed over the pixels;

a first glass substrate bonded to the frontside of the device substrate; and

a second glass substrate bonded to the backside of the device substrate.

14. The image sensor of claim 13, wherein the first glass substrate provides support for thinning and processing the device substrate from the backside.

15. The image sensor of claim 13, wherein the first and second glass substrates each has a thickness ranging from about 100 to about 1000 μ

m.

16. The image sensor of claim 13, wherein the device substrate has a thickness ranging from 1 to about 10 μ

m.

17. The image sensor of claim 13, further comprising:

a color filter layer disposed on the backside of the device substrate; and

a microlens layer disposed on the color filter layer;

wherein a cavity is formed between the second glass substrate and the device substrate and wherein the color filter layer and the microlens layer are disposed within the cavity.

18. The image sensor of claim 17, wherein the cavity is filled with one of air and epoxy.

19. The image sensor of claim 13, further comprising:

a re-distribution layer (RDL) disposed on the first glass substrate; and

a sidewall contact assembly for coupling the RDL and the interconnect structure.

20. The image sensor of claim 19, further comprising a board for coupling to the RDL for chip packaging.